business/src/main/resources/META-INF/MANIFEST.MF
tells the EJB3 server which classpath entries we need (in addition to the ones it provides).
business/src/main/resources/META-INF/persistence.xml
tells the EJB3 server how we want to persist data - the datasource name and some settings.
The collapser copies this file in from business/src/main/resources/persistence-descriptor
where there is a choice of files to suit different combinations of HSQL, MySQL, H2, or Derby, with
Hibernate, in OpenEJB, JBoss, or Glassfish. The collapser gets the one specified in build.properties.

The only one you're likely to change is persistence.xml. See Tips for more on that.

Tapestry expects a class called AppModule to exist to describe services we want added in: